Add prod Dockerfile based on Bun guide

Dockerfile.prod

@@ -0,0 +1,40 @@
+# Dockerfile for production deployments of Alexandria.
+# Based on the Bun Docker guide: https://bun.sh/guides/ecosystem/docker.
+
+# Use the official Bun image
+FROM oven/bun:1 AS base
+WORKDIR /usr/src/app
+
+# Install dependencies into temp directory.
+# This will cache them and speed up future builds.
+FROM base AS install
+RUN mkdir -p /temp/dev
+COPY package.json bun.lock /temp/dev/
+RUN cd /temp/dev && bun install --frozen-lockfile
+
+# Install with --production (exclude devDependencies)
+RUN mkdir -p /temp/prod
+COPY package.json bun.lock /temp/prod/
+RUN cd /temp/prod && bun install --frozen-lockfile --production
+
+# Copy node_modules from temp directory.
+# Then copy all (non-ignored) project files into the image.
+FROM base AS prerelease
+COPY --from=install /temp/dev/node_modules node_modules
+COPY . .
+
+# [Optional] Tests & build.
+ENV NODE_ENV=production
+RUN bun test
+RUN bun run build
+
+# Copy production dependencies and source code into final image.
+FROM base AS release
+COPY --from=install /temp/prod/node_modules node_modules
+COPY --from=prerelease /usr/src/app/index.ts .
+COPY --from=prerelease /usr/src/app/package.json .
+
+# Run the app.
+USER bun
+EXPOSE 3040/tcp
+ENTRYPOINT [ "bun", "run", "index.ts" ]